In a typical scroll compression apparatus, two interfitting involute scroll wraps are provided for forming a plurality of chambers moving from the radial outer ends of the scroll wraps to the radial inner ends of the scroll wraps. The chambers are formed by a plurality of moving line contacts generated between the flanks of the scroll wrap elements, with the tip of each respective scroll wrap element in sliding engagement with the end plate of the opposing scroll element. In operation, one scroll wrap orbits with respect to the other scroll wrap, causing the formation of a chamber at the radial exterior end into which fluid is drawn and compressed as the chamber grows smaller in volume toward the center of the scroll wraps. The compressed fluid is then discharged through an aperture centrally disposed in at least one of the end plates of the scroll wraps. Each chamber therefore discharges a pulse of compressed fluid, such that the output of compressed fluid from the scroll apparatus is pulsating in manner.
However, in order to maintain the desired pressure between the respective tips and end plates of the scroll wraps to minimize leakage therebetween, it has been found desirable to apply fluid at discharge pressure to act upon at least one of the scroll wrap end plates on the side opposite from the scroll wrap. The area to which the discharge pressure fluid is applied generally determines the pressure applied to the scroll wrap tips.
It has been found difficult to maintain the appropriate pressure due to variations in discharge pressure.
The discharge pressure varies in response to varying load conditions of the system in which the scroll compression apparatus is used. For example, in a refrigeration system the load experienced by the scroll compression apparatus is the flow of refrigerant fluid to be compressed. This flow varies in response to environmental temperature changes experienced by the condenser and evaporator, changes in refrigerant flow rate through the expansion valve, changes in the refrigeration system controller and other factors.
Furthermore, it is also desirable to minimize the effects of the occasional fluctuations in the suction pressure of the fluid to be compressed. When the suction pressure of the fluid is relatively higher or lower, it would be desirable to obtain a corresponding slight compensatory increase or reduction in the pressure exerted between the scrolls. Typically, no provision is made for these fluctuations.
Another problem often encountered in the typical pressure balanced scroll compression apparatus is leakage of fluid at discharge pressure to the area containing fluid at suction pressure. Not only does this leakage make difficult the maintenance of the appropriate pressure in the compressor apparatus, but any such fluid must be recompressed, reducing the useful work output of the scroll compression apparatus. Typical compressor apparatus utilize an elastomeric seal to minimize this leakage, however, the elastomeric seal is typically too inflexible to absorb any substantial axial movement of the scroll end plate due, for example, to slugging of fluid through the scroll wraps.
Therefore, it is an object of the present invention to provide a regulated pressure in a discharge pressure balanced scroll compression apparatus.
It is a further object of the subject invention to provide an improved sealing means for improving the efficiency of such a pressure balanced scroll compression apparatus.
It is yet a further object of the invention to provide an apparatus for regulating the discharge pressure balancing in such an apparatus.
It is yet a still further object of the present invention to provide such a pressure regulation device as will react to fluctuations in suction pressure.
It is a still further object of the invention to provide such an improved compression apparatus which is inexpensive to maintain and operate.
Yet a still further object is to provide such an apparatus which is self-contained and self-governing.
These and other objects of the invention will be apparent from the attached drawings and the description of the preferred embodiment that follows hereinbelow.